Conceptual developments in metabolic control, 1924-1974.

A brief sketch is given of the development of the understanding of the respiratory mechanism in plants over the past 50 years. Against this background the following aspects of control are discussed: (a) nonreversibility of catabolic sequences; (b) compartmentation of reactions and reactants; (c) control by amount of enzyme; (d) control by NAD and NADP; (e) control by ADP supply; (f) pacemaker reactions in glycolysis; and (g) control at branch points: further examples of allostery.